#include <iostream>
#include <string.h>

int main() {
    int alphabetic(char c);
    int longest(char[]);
    int i;
    char line[100];
    printf("Input one line: \n");
    gets(line);
    printf("The longest word is :");
    for (i = longest(line); alphabetic(line[i]); i++) {
        printf("%c", line[i]);
    }
    printf("\n");
    return 0;
}

int alphabetic(char c) {
    if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z'))
        return 1;
    else
        return 0;
}

int longest(char string[]) {
    int len = 0, i, length = 0, flag = 0, place = 0, point;
//    int alphabetic(char c);
    for (i = 0; i <= strlen(string); i++) {
        if (alphabetic(string[i]))
            if (flag) {
                point = i;
                flag = 0;
            } else len++;
        else {
            flag = 1;
            if (len >= length) {
                length = len;
                place = point;
                len = 0;
            }
        }
    }
    return (place);
}
